The present invention relates to photosensitive compositions which contain an additive to influence one or more physical and/or chemical properties of the composition. Such properties can include, without limitation adhesion, adhesion coupled with flexibility, printout contrast and stripping of the composition from a substrate.
Photosensitive compositions particularly useful as photoresists are well known in the prior art. Conventionally these compositions are stored in roll form. The composition is adhered to a support film to form a two ply material such as disclosed in U.S. Pat. No. 4,293,635 or more conventionally in a three ply material such as U.S. Pat. No. 3,469,982 with the composition sandwiched between a support film and a coversheet. The photosensitive composition contains components of monomer, initiator and a polymeric binder which allows such composition to be negative working (i.e., exposure to actinic radiation hardens the film to make the exposed portion insoluble in a developer solution). The material is conventionally unwound from a roll, and the cover sheet if present is removed from contact with the photosensitive composition prior to use in lamination to a substrate. e.g., in manufacture of printed circuit boards. The laminated composition is exposed imagewise to actinic radiation with a support film stripped from the photosensitive composition before or after the exposure step. The unexposed areas of the starting light-sensitive layer are washed away in a development step to form resist image of polymeric material. The exposed portion of the substrate is conventionally etched or plated followed by removal of the polymeric resist image.
The photosensitive composition can contain many additives including an adhesion promoter which improves the ability of the photosensitive composition to remain adhered to a substrate upon lamination and through subsequent processing slips.
U.S. Pat. No. 3,622,334 discloses a photopolymer resist composition which contains as an adhesion promoter a small amount of a heterocyclic nitrogen containing compound of the formula ##STR1## wherein R is substituted or unsubstituted ortho arylene, X is CH.sub.2, NH, S, O or Se; Z is N or C--Y and Y is H, NH.sub.2, halogen or alkyl.
A further disclosure of a photosensitive composition which contains a nitrogen containing compound is U.S. Pat. No. 4,298,678 This patent teaches incorporation into the photosensitive composition of a photooxidant leuco dye and a substituted hydroxylamine compound of the formula R.sub.1 R.sub.2 NOH where R.sub.1 and R.sub.2, e.g., are alkyl, cyclic alkyl, aryl, aralkyl, alkaryl and R.sub.1 and R.sub.2 taken together from a heterocyclic ring of 5 to 7 carbon atoms. Named compounds which include a heterocyclic ring are N-hydroxypyrolidine and N-hydroxypiperidine.